Laboratory Assessment of RSA and Baroreflex Sensitivity RSA and baroreflex sensitivity will be assessed noninvasively in the laboratory during a 10-minute baseline. Physiological channels required for their quantification will be recorded using (1) an ECG (400 Hz sample rate); (2) two channels of respiration using a Respitrace system (Ambulatory Monitoring, Ardsley, NY); bands are placed around the upper thorax and around the abdomen and calibrated against spirometry (25 Hz sample rate); (3) a continuous arterial blood pressure waveform from the index finger by means of the Finapres 2300 system.